Semi-trailers, flatbed trailers and chassis typically have a suspension that is considered to be either a fixed suspension or a sliding suspension. Fixed suspensions are typically attached to the trailer body in such a way that their position relative to the trailer body is considered a permanent configuration. Fixed suspensions are typically attached to the trailer body by welding or bolting the suspension rigidly into place. Sliding suspensions are typically attached to the trailer body in such a way that their position relative to the trailer body can be changed during operation. Sliding suspensions are typically attached to the trailer body using movable sub-frames commonly referred to as sliders. Sliding suspensions typically have a retractable pin mechanism that enables selective positioning of the slider relative to the trailer body during vehicle operation.
A prior art slider for a semi-trailer is indicated generally at 20 and is shown in FIG. 1. Slider 20 is movably mounted on trailer body 40 (FIGS. 3-4) by slidable engagement of rail guides to the trailer body main rails.
A prior art fixed suspension is shown in FIGS. 5-6. A typical fixed suspension is attached to the trailer body in fixed locations in such a way as dimensions A and B in FIG. 5 can not be changed.